Control method of air conditioner in electrical vehicle

ABSTRACT

A control method is provided for an air conditioning control system which includes determining whether either a desired discharge temperature from an air-conditioning system to maintain the internal temperature of a vehicle at a desired internal cabin temperature and a desired evaporator temperature that is temperature of an evaporator satisfies a heater operating condition. The heater is then operated in accordance with temperature and traveling conditions of the vehicle to output a desired discharge temperature when the heater operating conditions are satisfied. When, however, a heater discharge temperature from the heater is greater than or equal to a reference heater or the heater discharge temperature is greater than the desired discharge temperature by at least a predetermined temperature or more, then the heater is turned off to prevent over consumption of electricity.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a control method of an air conditioner, and more particularly, to a control method for an air conditioning system of an electric vehicle which prevents power from being consumed by a heater in the air conditioning system.

2. Description of Related Art

Recently, along with the increase in interest in development of environmentally-friendly energy, electric vehicles that use batteries as an energy source have also been spotlighted in the vehicle industrial field. One of the noted problems with electric vehicles is that they have a shortened driving range. This means, that the consumer may only be able to drive the vehicle for a few hundred miles before the vehicle must be recharged at a charging station. Sometimes, these charging stations are not readily accessible to the consumer and thus the consumer is not able to travel long distances from his or her home where the charging stations are located. Accordingly, there is a consistent need to continually look for new ways to increase the total driving distance range for a battery in electric cars, due to the batteries limited accumulation of condensation.

In electric vehicles, the internal cabin temperature of the vehicles is controlled by a separate electric heater and an air-conditioning system. In particular, power that is consumed by the air-conditioning system of an electric-vehicle is greater than that of engine-driven vehicles because the air-conditioning system in electric vehicles requires power consumption for separately driving the electric heater and the air-conditioning system even when it is hot in summer in order to control the internal temperature of the vehicles.

Therefore, that the air-conditioning systems in electric vehicles can and do greatly effect the driving range of the electric vehicles. Although the range can be increased by limiting the usage of the air-conditioning system by the user, this comes a cost to the occupant who might find themselves very uncomfortable especially on hot summer days.

The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

BRIEF SUMMARY OF THE INVENTION

The present invention has been made in an effort to provide a control method of an air conditioner that can prevent power from being consumed by driving a heater in an air conditioner by determining whether one or more heater cut-off conditions are satisfied from a desired discharge temperature, a desired evaporator temperature, an evaporator temperature, and a heater discharge temperature, and then cutting off the heater in response to a determination that one or more of these conditions are satisfied.

Further, the present invention has been made in an effort to provide a control method of an air conditioner that can reduce power consumption by an air-conditioning system in the electric vehicle which is generated when a heater and an air conditioner are simultaneously operating by delaying operation of the heater when the air conditioner is in operation.

An exemplary embodiment of the present invention provides a control method of an air conditioner, including determining, by a controller, whether either a desired discharge temperature from an air-conditioning system to maintain the internal cabin temperature of a vehicle at a desired internal temperature and a desired evaporator temperature that is an evaporator temperature satisfies a heater operating condition; controlling, by the controller, operation of the heater in accordance with temperature and traveling conditions of the vehicle to output the desired discharge temperature when the heater operating condition is satisfied; and cutting off operation of the heater when a measured heater discharge temperature of the heater is measured to be equal to or greater than a reference temperature or the heater discharge temperature is greater than the desired discharge temperature by a predetermined temperature or more when the heater is operated.

The control method may further include re-determining whether at least the desired discharge temperature and the desired evaporator temperature satisfy the heater driving condition after the heater operation is cut off; and in response initiating operation of the heater when the heater operation condition is satisfied and the desired discharge temperature is a first temperature or less and the heater discharge temperature is a first predetermined amount T₁, e.g., 15° C., lower than the desired discharge temperature.

Furthermore, when the heater operation condition is satisfied and the desired discharge temperature is above the first temperature, the heater may again be operated when the heater discharge temperature is lower than a second temperature. Additionally, when the desired evaporator temperature is a second predetermined amount T₂, e.g., 2° C., higher than the current measured evaporator temperature or the desired discharge temperature is a third predetermined amount T₃, e.g., 4° C. higher than the desired evaporator temperature, the heater driving condition may be determined to be satisfied.

The control method may further include an air-conditioning system driving determining and delaying step that keeps the heater “maxed out” for a predetermined time such that operation of the heater is performed after a predetermined time is passed when the air-conditioning system is being operated, as a result of determining whether the air-conditioning system is being operated after determining that a heater operating condition has been satisfied. Additionally, when it is determined that the air-conditioning system is not being operated the heater may then be controlled to operate in accordance with temperature and traveling conditions of the vehicle to output the desired discharge temperature when the heater operating condition is satisfied.

For example, the heater operation may be cut off when the heater discharge temperature is a predetermined temperature T₄, e.g., 85° C., or more, which is a reference temperature, or the heater discharge temperature is larger than the desired discharge temperature by a predetermined temperature, T₅, 20° C., or more, which is a predetermined temperature for cutting off power to the heater.

Advantageously, the control method of an air conditioner prevents power from being consumed by operation of a heater in an air conditioning system of an electric vehicle by determining whether one or more heater cut-off conditions are satisfied based a desired discharge temperature, a desired evaporator temperature, an evaporator temperature, and/or a heater discharge temperature, and then cutting off the heater in response to this determination. Further, according to the exemplary embodiments of the present invention can reduce the amount of power consumed by an air-conditioning system that is generated when a heater and an air conditioner are simultaneously operated by delaying operation of the heater while the air conditioner is in operation.

The methods and apparatuses of the present invention have other features and advantages which will be apparent from or are set forth in more detail in the accompanying drawings, which are incorporated herein, and the following Detailed Description of the Invention, which together serve to explain certain principles of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A and FIG. 1B are flowcharts illustrating a control method of an air conditioner according to an exemplary embodiment of the present invention.

FIG. 2 is a block diagram showing the configuration of an air-conditioning system for illustrating the control method of an air conditioner shown in FIG. 1A and FIG. 1B.

It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various features illustrative of the basic principles of the invention. The specific design features of the present invention as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes will be determined in part by the particular intended application and use environment.

In the figures, reference numbers refer to the same or equivalent parts of the present invention throughout the several figures of the drawing.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to various embodiments of the present invention(s), examples of which are illustrated in the accompanying drawings and described below. While the invention(s) will be described in conjunction with exemplary embodiments, it will be understood that present description is not intended to limit the invention(s) to those exemplary embodiments. On the contrary, the invention(s) is/are intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the invention as defined by the appended claims.

Exemplary embodiments of the present invention are described hereafter with reference to the accompanying drawings, for those skilled in the art to easily implement the present invention.

It is understood that the term “vehicle” or “vehicular” or other similar term as used herein is inclusive of all electrically operated vehicles including fuel cell and hybrid vehicles and any configuration thereof in general, such as passenger automobiles including sports utility vehicles (SUV), buses, trucks, various commercial vehicles, watercraft including a variety of boats and ships, aircraft, and the like. Further, this invention can also be modified to operate in fuel-computation vehicles as well. However, the examples below will be described with reference to an electric vehicle utilizing a battery as its main source of power.

Referring to FIGS. 1A, 1B, and 2, an air-conditioning controller 110 is installed and configured to calculate a desired discharge temperature, T_(o), for discharged air from an air conditioning system 100 and a desired evaporator temperature, T_(eo), of a evaporator in air-conditioner (air con) 130, in order for a driver to maintain a desired internal temperature within the cabin of the vehicle.

Air-conditioning controller 110 performs a driving condition determining step S1 that determines whether either the desired discharge temperature T_(o) or the desired evaporator temperature T_(eo), which were previously calculated by the air-conditioning controller 110, satisfy an operation condition for operating a heater within the air conditioning system 100. The air-conditioning controller 100 in the exemplary embodiment may be a controller of an FATC (Full Automatic Temperature Control) that controls operation of electronic devices such as a heater 120 and the air-con 130, which are each separate devices in the air conditioning system 100, in accordance with the state and temperature of the vehicle which are supplied from various sensors (not shown) in the vehicle.

For example, in the driving condition determining step S1, the air-conditioning controller 110 may determine that a heater driving condition has been satisfied, when, for example, the desired evaporator temperature T_(eo) is T₂ degrees, e.g., 2° C., higher than the evaporator temperature T_(e) measured from the evaporator in the air-con 130 or the desired discharge temperature T_(o) is T₃, e.g., 4° C., higher than the desired evaporator temperature T_(eo). The air-conditioning controller 110 may determine whether the desired evaporator temperature T_(eo) is larger than a first value obtained by adding T₂, e.g., 2° C., to the evaporator temperature T_(e) (S11) and determine that the heater driving condition is satisfied when the desired evaporator temperature T_(eo) is larger than the first value obtained by adding T₂, e.g., 2° C. to the evaporator temperature T_(e).

The air-conditioning controller 110 may determine whether the desired discharge temperature T_(o) is larger than a second value obtained by adding T₃, e.g., 4° C., to the desired evaporator temperature T_(eo), when the desired evaporator temperature T_(eo) is equal to or smaller than the first value obtained by adding T₂ to the evaporator temperature T_(e) (S12). If T_(o) is not larger than a second value obtained by adding T₃, e.g., 4° C., to the desired evaporator temperature T_(eo), the controller repeats steps (S11) and (S12) until one of the defined conditions are satisfied. In particular, the air-conditioning controller 110 determines that the heater operation condition has been satisfied when the desired discharge temperature T_(o) is larger than the value obtained by adding, T₂, e.g., 4° C., to the desired evaporator temperature T_(eo). Alternatively, when it is determined that the heater operation condition is not satisfied, heater 120 is kept turned off (S5) and the controller repeats steps (S11) or (S61) and (S12) or (S62) until one of the heater operation conditions are satisfied. When it is determined that one of the heater operation conditions are satisfied in the driving condition determining step (S1), the controller then may, in some embodiments like the one shown in FIG. 1A, additionally determine whether air-con 130 is currently being operated (S21) and an air-con driving determining and delaying step (S2) that keeps heater 120 stopped for a predetermined time in accordance with whether air-con 130 is driven is performed.

First, when it is determined that air-con 130 is not being operated (S21), a heater operation control step (S3) that controls the operation of heater 120 in accordance with the temperature and traveling conditions of the vehicle is performed to output the desired discharge temperature T_(o). When it is determined that air-con 130 is operated (S21), the air-conditioning controller 110 drives a timer t. The air-conditioning controller 110 determines whether a certain operational time has passed a predetermined time t_(o) from timer t (S23), and when the predetermined time t_(o) of timer t has passed, a heater operating control step (S3) that controls operation of heater 120 is performed by the controller 110. The predetermined time t_(o) may be set at 1 minute, for example.

That is, when air-con 130 is operated in conjunction with the air-con driving determining and delaying step/program (S2, the heater driving control step (S3) that controls driving of heater 120 may be performed after heater 120 is kept stopped for the predetermined time t_(o) in which the temperature of the evaporator is led to be decreased by, e.g., reducing the operational RPM of a compressor of air-con 130.

The air-conditioning controller 110 controls the operation of heater 120 which may be embodied as a Positive Thermal Coefficient (PTC) heater so that the temperature of air supplied from air conditioning system 100 into the vehicle is controlled to become the desired discharge temperature To in accordance with the temperature of the internal/external air and conditions of the vehicle. The air-conditioning controller 100 controls the temperature of the air discharged from heater 120 by controlling a operation signal supplied to heater 120 in a PWM (Pulse Width Modulation) type arrangement in order to control the discharge temperature of air conditioning system 100 to the desired discharge temperature T_(o).

While the heater is operating, a heater cut-off determining step (S4) is performed. This step (S4), cuts off driving of heater 120 when the heater discharge temperature T_(p), which is continually increased by driven heater 120, is greater than or equal to a reference temperature T₄ or when the heater discharge temperature Tp is greater than or equal at a predetermined temperature T₅ plus a desired discharge temperature T_(o).

For example, the air-conditioning controller 110 may determine whether the heater discharge temperature Tp is 85° C. or more, which is the reference temperature T₄, in the heater cut-off determining step (S41), and when it is determined that the heater discharge temperature Tp is T₄ or more, the heater is turned off (S5) by turning off the heater (S43) to prevent heater 120 from becoming overheated. The reference temperature T₄ may be set at different values in accordance with the driving characteristics of the air-conditioning system of vehicles and the environment in which the vehicle is currently or has previously been driving in.

When it is determined that the heater discharge temperature Tp is less than the reference temperature T₄ in step (S4), the air-conditioning controller 110 then determines whether the heater discharge temperature Tp is greater than or equal to the desired discharge temperature T_(o) plus T₅ (e.g., 20° C.), is the combination of which a predetermined temperature. When the heater discharge temperature T_(p) is greater than or equal to a value obtained by adding T₅ to the desired discharge temperature T_(o), the heater is turned off (S5) by turning off the power supply to the heater (S43) in order to prevent further power consumption from being generated by overheating the heater 120.

When the heater discharge temperature T_(p) is less than the reference temperature T₄ and less than a value obtained by adding a predetermined temperature T₅ to the desired discharge temperature T_(o), the controller may be configure to then perform the heater driving control step (S3) that controls the desired discharge temperature To through the heater discharge temperature Tp by operation of the heater 120.

In order to determine a cut-off removal condition for re-operating the heater 120 when the heater 120 is turned off and kept turned off (S5) in (S4), an operating condition re-determining step (S6) that re-determines whether either the desired discharge temperature T_(o) or the desired evaporator temperature T_(eo) satisfies the heater operation conditions. In the operation condition re-determining step S6, the air-conditioning controller 110 determines whether the heater re-operation condition is satisfied, when the desired evaporator temperature T_(eo) is T₂ (e.g., 2° C.) higher than the evaporator temperature T_(e) or the desired discharge temperature T_(o) is T₃ (e.g., 4° C.) higher than the desired evaporator temperature T_(eo).

In the driving condition re-determining step (S6), the air-conditioning controller 110 determines whether the desired evaporator temperature T_(eo) is larger than a first value obtained by adding T₂ (e.g., 2° C.) to the evaporator temperature T_(e). Further, when the desired evaporator temperature T_(eo) is greater than the first value obtained by adding T₂ (e.g., 2° C.) to the evaporator temperature T_(e), it is determined that the heater re-driving condition is satisfied, and a cut-off removal determining step (S7) is performed. In doing so, the controller 110 determines whether the condition for removing cut-off of heater 120 is satisfied.

The air-conditioning controller 110 determines whether the desired discharge temperature T_(o) is greater than a second value obtained by adding T₃ (e.g., 4° C.) to the desired evaporator temperature T_(eo), when the desired evaporator temperature T_(eo) is equal to or less than the first value obtained by adding T₂ (e.g., 2° C.) to the evaporator temperature (S62). Further, when the desired discharge temperature T_(o) is greater than the second value obtained by adding T₃ (e.g., 4° C.) to the desired evaporator temperature T_(eo), the air-conditioning controller 110 then determines that the heater operating conditions are satisfied, and a cut-off removal determining step (S7) is performed to determines whether the conditions for removing cut-off (turning on) of heater 120 is satisfied.

In the driving condition re-determining step (S6), when it is determined that the heater driving condition is not satisfied, heater 120 is kept turned off (S5), in a cut-off state. When the desired discharge temperature T_(o) is a T₆ (e.g., 64° C.) or less in the cut-off removal determining step (S7), it is determined whether the heater discharge temperature T_(p) is T₁(e.g., 15° C.) lower than the desired discharge temperature T_(o) (S71). When the desired discharge temperature T_(o) less than or equal to T₆ and the heater discharge temperature T_(p) is less than a value obtained by adding T₁(e.g., 15° C.) to the desired discharge temperature T_(o), it is determined that the heater cut-off removal condition is satisfied. The T₆ may be set to 64° C., for example. More specifically, temperature T₆ is a tuning value for the desired discharge temperature T_(o) and may be set in accordance with the temperature control characteristics of the air conditioning system 100.

Preferably, when the heater 120 is a PTC heater, the temperature is not increased immediately even if power is supplied, thus when the heater discharge temperature T_(p) (measured now from heater 120) is less than the value obtained by adding T₁(e.g., 15° C.) to the desired discharge temperature T_(o), the heater 120 may be turned back on (remove heater cut-off) (S73) to easily control the discharge temperature from the air conditioning system 100 to the desired discharge temperature T_(o) by allowing early for heating of the heater 120.

When the desired discharge temperature T_(o) is greater than T₆, the controller 110 determines whether the heater discharge temperature T_(p) is less than or equal to T₇ (e.g., 84° C.) (S72), and when the desired discharge temperature To is above T₆ and the desired discharge temperature T_(p) is less than or equal to T₇, it is determined that the cut-off removal condition is also satisfied. T₇ may be set to 84° C., for example.

When the desired discharge temperature T_(o) is greater than the T₆, the heater 120 is operated earlier in comparison to when it is the T₆ or less, and when the heater discharge temperature T_(p) is T₇ or less, it is determined that the heater cut-off removal condition is satisfied and the heater 120 is turned back on (S73). When the cut-off of heater 120 is removed (i.e., the heater 120 is turned back on), the heater driving control step (S3) that controls the operation of heater 120 is again operated so that the temperature of the air supplied into the vehicle becomes the desired discharge temperature T_(o).

Advantageously, the present invention is able to prevent power from being consumed by operation of the heater 120 by turning off the heater 120 when certain temperature dependent and/or time dependent conditions are satisfied. These conditions are based on a desired discharge temperature T_(o), a desired evaporator temperature T_(eo), an evaporator temperature T_(e), and a heater discharge temperature T_(p). Further, the present invention can reduce the amount of power consumed by an air-conditioning system which is generated when a heater and an air conditioner are simultaneously operated by delaying operation of the heater when the air conditioner is in operation.

Furthermore, the present invention may be embodied as computer readable media on a computer readable medium in an on-board computation unit containing executable program instructions executed by a processor. Examples of the computer readable mediums include, but are not limited to, ROM, RAM, compact disc (CD)-ROMs, magnetic tapes, floppy disks, and optical data storage devices. The computer readable recording medium can also be distributed in network coupled computer systems so that the computer readable media is stored and executed in a distributed fashion.

The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and their practical application, to thereby enable others skilled in the art to make and utilize various exemplary embodiments of the present invention, as well as various alternatives and modifications thereof. It is intended that the scope of the invention be defined by the Claims appended hereto and their equivalents. 

1. A control method of an air conditioner, comprising: determining, by a controller, whether at least one of a desired discharge temperature from an air-conditioning system to maintain the internal temperature of a vehicle at a desired internal temperature and a desired evaporator temperature that is the temperature of an evaporator satisfy a heater operating condition; controlling, by the controller, the operation of the heater in accordance with temperature and traveling conditions of the vehicle to output the desired discharge temperature when the heater operating conditions are satisfied; and turning off, by the controller, the heater when a heater discharge temperature from the heater is a reference temperature or more or the heater discharge temperature is larger than the desired discharge temperature by a predetermined temperature or more when the heater is driven.
 2. The method as defined in claim 1, further comprising: in response to turning off the heater, initiating a process which re-determines whether at least the desired discharge temperature and the desired evaporator temperature satisfies the heater operating condition; and turning on the heater when the heater operation condition is satisfied and the desired discharge temperature is less than or equal to a first temperature T₆ and the heater discharge temperature is less than the desired discharge temperature plus 15° C.
 3. The method as defined in claim 2, wherein when the heater operating condition is satisfied and the desired discharge temperature is greater than the first temperature T₃, the heater is turned back on when the heater discharge temperature is lower than a second temperature T₇.
 4. The method as defined in claim 2, wherein when the desired evaporator temperature is 2° C. higher than the currently measured evaporator temperature or the desired discharge temperature is 4° C. higher than the desired evaporator temperature, the controller determines that the heater operating condition is satisfied.
 5. The method as defined in claim 1, further comprising keeping the heater at maximum capacity for a predetermined time so that the heater may be controlled after a predetermined time is passed when a air-conditioner in the air-conditioning system is operated, as a result of determining whether the air-con is operated when the operation condition is satisfied in determining of the operating condition.
 6. The method as defined in claim 5, wherein the heater control is performed when the controller determines that the air-con has not been operated.
 7. The method as defined in claim 1, wherein the heater is turned off when the heater discharge temperature is 85° C. or more, which is a second reference temperature T₄, or the heater discharge temperature is greater than the desired discharge temperature by at least 20° C., which is a predetermined temperature T₅.
 8. An air-conditioning system for a vehicle, comprising: a heater configured to output a temperature T_(o); an evaporator in an air conditioner configured to output a temperature T_(e); a controller configured to determine whether at least one of a desired discharge temperature from an air-conditioning system and a desired evaporator temperature satisfy a heater operating condition, control the operation of the heater in accordance with temperature and traveling conditions of the vehicle to output the desired discharge temperature when the heater operating condition is satisfied; and turning off the heater when a heater discharge temperature from the heater is greater than a reference temperature T₂ or that the heater discharge temperature is greater than the desired discharge temperature plus a predetermined amount T₃ while the heater is being operated.
 9. The air-conditioning system as defined in claim 8, wherein the controller is further configured to initiating a process which re-determines whether at least the desired discharge temperature and the desired evaporator temperature satisfies the heater operating condition in response to turning off the heater, and turn on the heater when the heater operation condition is satisfied and the desired discharge temperature is less than or equal to a first temperature T₆ and the heater discharge temperature is less than the desired discharge temperature plus 15° C.
 10. The air-conditioning system as defined in claim 9, wherein when the heater operating condition is satisfied and the desired discharge temperature is greater than the first temperature T₃, the heater is turned back on when the heater discharge temperature is lower than a second temperature T₇.
 11. The air-conditioning system as defined in claim 9, wherein when the desired evaporator temperature is 2° C. higher than the currently measured evaporator temperature or the desired discharge temperature is 4° C. higher than the desired evaporator temperature, the controller determines that the heater operating condition is satisfied.
 12. The air-conditioning system as defined in claim 8, wherein the controller is further configured to keep the heater at maximum capacity for a predetermined time so that the heater may be controlled after a predetermined time is passed when a air-conditioner in the air-conditioning system is operated, as a result of the determination whether the air-con is operated when the operation condition is satisfied in the determination of the operating condition.
 13. The air-conditioning system as defined in claim 12, wherein heater control is performed when the controller determines that the air-con has not been operated.
 14. The air-conditioning system as defined in claim 8, wherein the controller is configured to turn off the heater when the heater discharge temperature is 85° C. or more, which is a second reference temperature T₄, or the heater discharge temperature is greater than the desired discharge temperature by at least 20° C., which is a predetermined temperature T₅.
 15. The in air-conditioning system as defined in claim 8 wherein the heater is a Positive Thermal Coefficient (PTC) heater.
 16. A computer readable medium containing executable program instructions executed by a processor, comprising: program instructions that determine whether at least one of a desired discharge temperature from an air-conditioning system to maintain the internal temperature of a vehicle at a desired internal temperature and a desired evaporator temperature that is the temperature of an evaporator satisfy a heater operating condition; program instructions that control the operation of the heater in accordance with temperature and traveling conditions of the vehicle to output the desired discharge temperature when the heater operating conditions are satisfied; and program instructions that turn off the heater when a heater discharge temperature from the heater is a reference temperature or more or the heater discharge temperature is larger than the desired discharge temperature by a predetermined temperature or more when the heater is driven. 